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Mast Cell Activation Syndrome (MCAS)

What is mast cell activation syndrome?

Mast cell activation syndrome (MCAS) is a condition that is characterized by episodes of allergic symptoms, such as hives and swelling. Mast cells, which are in charge of allergic reactions, are defective in people affected by MCAS. 

What are the symptoms of mast cell activation syndrome?

Symptoms include:

  • Low blood pressure
  • Fainting
  • Rapid pulse
  • Diarrhea
  • Nausea and vomiting
  • Abdominal pain
  • Shortness of breath/wheezing
  • Swelling in the throat
  • Hives
  • Itching
  • Swelling
  • Skin turning red

What causes mast cell activation syndrome?

Medical professionals are unsure of the cause of this condition, although they do suspect that there is a genetic component. Mast cells are defective and cause idiopathic allergic reactions, but it is not known why this happens. 

How is mast cell activation syndrome diagnosed?

A diagnosis can be difficult to obtain. Doctors will start with a physical exam, evaluation of medical history, and look for the characteristic symptoms. They have diagnostic criteria: MCAS treatments must relieve symptoms, symptoms are recurrent and affect two body systems, and blood and urine tests show high levels of mediators when someone is not having an episode. 

What are the treatments for mast cell activation syndrome?

The goal of treatment is to relieve the patient of symptoms. If a patient is in the midst of an episode, the first step is to administer epinephrine. Other treatments include antihistamines, aspirin, histamine type 2, montelukast, zafirlukast, omalizumab, and corticosteroids. 

Where can I find out more about mast cell activation syndrome?

MCAS Articles